Lead screw tapping head



957 D. c. KRAHNKE 2,799,872

- LEAD SCREW TAPPING HEAD Filed NQY. 19, 1954 v 2 Sheets-Sheet 3.

3nnentor DELBERT CARL KRAl-INKE JPMWw/lfimwr (Ittomeg July 23, 1957 D. c. KRAHNKE 2,799,872

LEAD SCREW TAPPING HEAD Filed NOV. 19, 1954 2 sheets sheet 2 ZOA 6 516.5 50A FI6.6

unuu Imnentor DELBERT CARL KRAHNKE attorney IQEAD SDREW TAPPING HEAD Delbert Carl Krahnke, Providence, R. 1.

Application November 19, 1954, Serial No. 469,888

7 Claims. (Cl. 1tl139) This invention relates to a lead screw tapping head and particularly to a lead screw tapping head having a planetary drive.

One of the objects of the present invention is to provide a long wearing, inexpensive, positive drive for a tapping head.

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2,799,872 Patented July 23, 1957 ICC and the teeth of sun gear 16 engage in what could be termed a sliding splined relationship.

Externally bushing 20 is provided with a shoulder 21 on one end and a groove housing a spring ring 22 on the other end. The race 23 of a ball bearing is fixed between shoulder 21 and spring ring 22.

First section 11 is provided with a shoulder 24 and a groove housing a spring ring 25 between which a ball bearing race '26 is firmly held. First section 11 is pro- 0 vided with a core 27 through which passes end 14 of Still another object of the invention is to provide a forward and rearward movement of a rotating shaft which is in a direct ratio to the speed of rotation of that shaft.

Other objects of the present invention will be pointed out in part and become apparent in part in the following specification and claims.

Tapping heads in the past had the lead screw as an integral part of the spindle. The lead screw, therefore, rotated at the speed of the spindle. This resulted in the rapid wear of the lead screw which necessitated costly replacement of the lead screw and its associated parts. The present invention overcomes this undesirable condition by providing a planetary drive for the advancement of the lead screw in an approximate ratio of nine to one. That is, for every nine revolutions of the tapping head spindle, the lead screw makes one revolution. The reduction in lead screw wear is obvious.

Like reference numerals refer to like parts in the accompanying drawings in which:

Figure 1 is a horizontal cross sectional view of the new 1inddimproved planetary drive for a lead screw tapping Figure 2 is a transverse sectional view taken along line 22 of Figure 1.

Figure 3 is a transverse sectional view taken along line 33 of Figure 1.

Figure 4 is a horizontal cross sectional view showing a modified form of Figure 1.

Figure 5 is a fragmentary horizontal cross sectional view showing another modified form of Figure 1.

Figure 6 is a fragmentary horizontal cross sectional view showing still another modified form of Figure 1.

Figure 7 is a transverse cross sectional view takenalong line 77 of Figure 4.

In proceeding with this invention a hollow housing is provided in the form of a first section 11 and a second section 12. A spindle passes through the housing, the end 14 of which is attached to any means of motor power such as -a portable motor or the chuck of a drill press.

The spindle axially is provided with a spur gear hereinafter termed the sun gear 16. The spindle is also provided with a bearing 13 adjacent a ball bearing retaining section 17 which terminates in a threaded portion 19. A tap chuck is attached to the (left hand in Figure 1) end 15 of the spindle.

A bushing is provided internally with spur gear teeth which engage sun gear 16. Bushing 20 is rotatively driven by sun gear 16 while permitting the gear teeth of sun gear 16 to slide longitudinally along the gear teeth in bushing 28. Bushing 20 is held in a fixed position within first section 11; The gear teeth in bushing 20 the spindle. Race 23 rotates in relation to race 26 through ball bearings 28.

A ring gear 30 with teeth 32 is interposed and held in position between firstsection 11 and second section 12 by means of bolts 31.

The core of second section 12 is provided with gear teeth 33 and a bearing 34. A lead screw 40 is provided, having teeth 41 which engage teeth 33 and a sleeve 42 which slidably engages bearing 34. Lead screw '40 is a threaded member or feed screw which advances the spindle. Adjacent teeth 41 is a shank 43 with an external contour formed into a male spline. A bushing 44 is formed in shank 43. It accommodates bearing 13 of the spindle. A chamber 45 forms a wall 46 at the junction of bushing 44.

A ball bearing 47 is secured in chamber 45, abutting wall 46 and is fixed to ball bearing retaining section 17 of the spindle. A second ball bearing 48 is secured in chamber 45 and is fixed to ball bearing retaining section 17 of the spindle. A groove in the body of the lead screw 40 at the entrance of chamber 45 houses a spring ring 50 which abuts ball bearing 48. A spacing collar 51 is mounted on ball bearing retaining section 17 abutting and separating ball bearings 47 and 48. A lock nut 49A engages threads 19 and secures ball bearings 47 and 48 in position on section 17 of the spindle.

A planet mount or spider 56 is axially provided with the female form of a spline which is slidably mounted to the male spline in shank 43. Three planet gears 57, 58, 59 are formed in the ends of stub shafts, such as stub shaft 49, see Figure 1. Planet gears 57, 58, 59 are rotatively mounted in spider 56 and they engage ring gear 30 which is a stationary gear. Three drive gears 60, 61, 62 are splined to said stub shafts (see stub shaft 49, Figure 1) and are retained thereon by means of spring rings 63. Drive gears 60, 61, 62 engage sun gear 16 and are driven by it.

In operation power will be applied to right hand end 14, thereby turning the spindle at a determinable R. P. M. Sun gear 16 will drive bushing 20 frictionlessly rotating on ball bearings 28. Sun gear 16 will also rotate drive gears 60, 61, 62 which in turn will rotate planet gears 57, 58, 59 engaging ring gear 30 and thereby rotate lead screw 40 through the spline in shank 43. Teeth 41 in lead screw 40 engaging teeth 33 in second section 12 of the housing will cause the lead screw 40 to advance in a ratio determined by the speed of the spindle and the gears of the planetary drive.

Ring gear 30, planet mount 56, planet gears 57, 58, 59 and drive gears 68, 61, 62 form a planetary drive. The modified form shown in Figure 4 modifies the planetary drive by eliminating the planet gears thereby compelling the drive gears to directly engage the ring gear 30A.

Figure 4 shows gear teeth 69 cut in the periphery of bushing 20A. Drive gears 60A, 61A, 62A engage ring gear 30A and gear teeth 69. Otherwise the operation is as previously described. Drive gears 60A, 61A, 62A engage gear teeth 69 in the bushing instead of the gear teeth 16 of the spindle. In the modified form shown in Figure 5 the gear teeth 69B are cut in bushing 2013. Drive gears 60, 61 and 62 of the form shown in Figures 1, 2 and 3 engage gear teeth 69B in the bushing instead of the changes can be made without departing from either the spirit or scope'of this invention. 7

What I claim is: 1. A lead screw tapping head comprising a housing,

bearing means in said housing, a spindle rotatable in said bearing means, a tap of a prescribed lead fixed to one end of said spindle, drive means applied at the other end of said spindle, a feed screw means for feeding said spindle and tap axially, which comprises a threaded member rotatable on said spindle but axially fixed with respect thereto and a cooperating threaded member fixed in said housing, the lead of said threaded members being a multiple of and greater than the lead of the tap, and reduction gearing between said spindle and threaded member for rotating it at a speed to feed the tap the distance of its lead for each revolution of the spindle.

2. A lead screw tapping head comprising a'housing having lead screw teeth axially provided in one end, a spindle rotatively and slidably mounted in said housing and provided with a sun gear, a ring gear fixed in said housing, a lead screw secured to said spindle for rotation with said spindle and engaging said lead screw teeth, a planet mount secured to said lead screw with a sliding fit to rotatively drive said lead screw, planet gears rotatively mounted in said planet mount engaging said'sun gear and said ring gear to impart the rotation of said spindle to said lead screw and through engagement of said lead screw with said lead screw teeth'to move said shaft longitudinally inrelation to said housing.

3. A lead screw tapping head comprising a housing, having lead screw teeth axially provided in one end, a spindle rotatively and slidably mounted in said housing, means on said spindle providing a sun gear, a ring gear fixed in said housing, a lead screw rotatively mounted on said spindle and engageable with the lead screw teeth in said housing, a planet mount rotatably mounted on said lead screw for longitudinal movement of said lead screw within said planet mount; planet gears rotatively mounted planet mount through a drive connection between said sun rotation in said first bearing with said teeth projecting in said planet mount and having means for rotating said and secured in said chamber to support said shaft in said second section of said housing, a planet mount secured to said shank for sliding movement of said shank within said planet mount, a multiple number of planet gears and a multiple number of drive gears rotatively mounted with a drive gear driving a companion planet gear in said planet mount, said planet gears rotatively engaging said ring gear and said drive gears rotatively engaging said sun gear whereby the rotation of said spindle will rotate through said drive gears, planet. gears, ring gears and planet mount to advance said lead screw longi-v tudinally in relation to said second section through engagement with said lead screw teeth.

5. A lead screw tapping head comprising a housing having a first section and a second section, a lead screw thread provided in said second section, a ring gear secured between said first section and said second section, a first bearing means in said first section, a lead screw provided with a shank, a second bearing means in said lead screw, a spindle rotatably mounted in said first and second bearing means and provided with sun gear teeth in one section of the periphery, a planet mount fixed to said shank for sliding movement of said shank within said planet mount, a multiple number of drive gears rotatably mounted in said planet mount and rotatably engaging both said ring gear and said sun gear teeth, whereby rotation of said spindle will rotate said drive gears to rotate said planet mount which will rotate said lead screw engaging said lead screw thread to move said spindle longitudinally of said housing.

6. A lead screw tapping head comprising a housing having a first section and a second section, a lead screw thread provided in said second section, a ring gear secured between said first section and said second section, a first bearing secured in said first section, a bushing having sun gear teeth on one external'end mounted for beyond the width of said first bearing, a lead screw pro-v vided with 'teeth engageable for rotation with said lead screw thread, said lead screw having a shank provided axially with a bushing, a chamber formed axially in said lead screw adjacent said bushing, a second bearing located in said chamber and secured to said lead screw, a spindle splined to said bushing to slide in said bushing and to rotatively drive said bushing, said spindle rotatively mounted in said second bearing, a third bearing formed on said shaft between said spline and said third bearing rotatably engaging said bushing, a planet mount fixed to said shank for sliding movement of saidshank within said planet mount, a multiple number of drive gears rotatably mounted in said planet mount, rotatably engaging both gear and said ring gear whereby rotation of the spindle will longitudinally move said lead screw and said spindle in relation to said housing through the drive connection of said planet mount and through the engagement of said lead screw mounted on said spindle with said lead screw teeth axially provided in said housing.

4. A lead screw tapping head comprising a housing having a first section and a second section, lead screw teeth axially provided in said second section, a ring gear secured between the first and second sections, a spindle provided axially with a sun gear adjacent one end, a ball bearing retaining section adjacent the other end and a bearing therebetween, a bushing provided internally with gear teeth for engagement and rotation with said sun gear and for sliding movement of said sun gear within said bushing, a ball 7 bearing fixed between said bushing and said first section to support said shaft in said first section of said housing, a lead screw provided with teeth engageable with the lead screw teeth in said second section and having a shank cured to said ball bearingretaining section and located said ring gear and said sun gear, whereby rotation of said spindle will through said sun gear on said bushing drive said. multiple, number of drive gears, said drive gears engaging said ring gear rotating said planet mount and through said shank rotate said lead screw which through engagement with said lead screw thread advance said lead screw longitudinally of said second section of said housing. 7. A lead screw tapping head comprising a housing having a first section and a second section, a lead screw thread provided in said second section, a ring gear secured between said first section and said second section, a.

first bearing means in said first section, a bushing having gear teeth on one end rotatively mounted in said first bearing, a lead screw having a shank provided axially with a bushing, a chamber located axially in said lead screw adjacent said bushing, a second bearing means located in said chamber and secured to said lead screw, a spindle rotatably mounted in said second bearing means, said spindle being splined to said bushing to slide in said bushing to drive said bushing, a planet mount fixed to said shank for sliding movement of said shank within said planet mount, a multiple number of drive gears and a multiple number of planet gears oppositely disposed in pairs on opposite sides of said planet mount, each pair of gears having a common shaft rotatably held in said planet mount, said spindle driving said bushing to rotate said drive gear, shaft, planet gears and planet mount, said planet gears engaging said ring gear, said planet mount rotating said lead screw whereby said lead screw engaging said lead screw thread will advance said spindle longitudinally of said housing.

References Cited in the file of this patent UNITED STATES PATENTS 

